GNU parallel is a shell tool for executing jobs in parallel locally or using remote machines. A job is typically a single command or a small script that has to be run for each of the lines in the input. The typical input is a list of files, a list of hosts, a list of users, a list of URLs, or a list of tables. A short video displaying the most common usage is available at: http://www.youtube.com/watch?v=OpaiGYxkSuQ.
Clipping is a handy way to collect important slides you want to go back to later.